Of carbostyril derivatives, many of them have hitherto been known to have useful pharmacological activities. For example, those carbostyril derivatives having a side chain similar to the side chain of the carbostyril derivative of the present application, represented by the formula ##STR2## and having a platelet aggregation inhibitory activity as the pharmacological activity, are disclosed in U.S. Pat. No. 4,070,470, U.S. Pat. No. 4,216,220, U.S. Pat. No. 4,313,947, U.S. Pat. No. 4,298,739, U.S. Pat. No. 4,435,404; British Patent No. 1,505,305, British Patent No. 2,002,745, British Patent No. 2,070,588; German Patent No. 2,527,937, German Patent No. 2,825,048, German Patent Laid-Open No. 3049959.3; Japanese Patent Kokai (Laid-Open) No. 51-23271 (1976), Japanese Patent Kokai (Laid-Open) No. 51-23272 (1976), Japanese Patent Kokai (Laid-Open) No. 51-136676 (1976), Japanese Patent Kokai (Laid-Open) No. 54-5981 (1979), Japanese Patent Kokai (Laid-Open) No. 54-12385 (1979), Japanese Patent Kokai (Laid-Open) No. 54-115383 (1979), Japanese Patent Kokai (Laid-Open) No. 58-23622 (1983), Japanese Patent Kokai (Laid-Open) No. 54-163825 (1979), Japanese Patent Kokai (Laid-Open) No. 55-35018 (1980), Japanese Patent Kokai (Laid-Open) No. 55-76864 (1980), Japanese Patent Kokai (Laid-Open) No. 55-79370 (1980), Japanese Patent Kokai (Laid-Open) No. 55-79371 (1980), Japanese Patent Kokai (Laid-Open) No. 55-79372 (1980), Japanese Patent Kokai (Laid-Open) No. 56-122356 (1981), Japanese Patent Kokai (Laid-Open) No. 57-2274 (1982 ), Japanese Patent Kokai (Laid-Open) No. 57-93962 (1982), Japanese Patent Kokai (Laid-Open) No. 57-175168 (1982), Japanese Patent Kokai (Laid-Open) No. 57-183761 (1982), Japanese Patent Kokai (Laid-Open) No. 59-46202 (1984), etc.
Also, those compounds which have a side chain similar to the side chain of the carbostyril derivative of the present application, represented by the formula ##STR3## and have a platelet aggregation inhibitory activity as the pharmacological activity but are not carbostyril derivatives, are disclosed in Japanese Patent Kokai (Laid-Open) No. 55-2655 (1980) (quinoline type compounds), Japanese Patent Kokai (Laid-Open) No. 54-115370 (1979) (oxyindole type compounds), Japanese Patent Kokai (Laid-Open) No. 57-14578 (1982) (benzimidazole-2-one type compounds), Japanese Patent Kokai (Laid-Open) No. 57-209281 (1982) (benzoxazine type compounds), Japanese Patent Kokai (Laid-Open) No. 55-36444 (1980) (thiocarbostyril type compounds), etc.
Further, those carbostyril derivatives having no side chain similar to the side chain of the carbostyril derivative of the present application, represented by the formula ##STR4## but having a platelet aggregation inhibitory activity as the pharmacological activity, for example, tetrazole-substituted alkoxycarbostyril derivatives are disclosed in U.S. Pat. No. 4,277,479, British Patent No. 2,033,893 and German Patent No. 2934747, and heterocycle-substituted alkoxycarbostyril derivatives are disclosed in European Patent Publication No. 0240015. Besides, those carbostyril derivatives having a side chain represented by the formula ##STR5## and having a platelet aggregation inhibitory activity, are disclosed in Japanese Patent Kokai (Laid-Open) No. 57-14574 (1982).
Further, U.S. Pat. No. 3,682,920 discloses 3,4-dihdyrocarbostyril derivatives having a substituent at the 1-position which are useful as an analgesic.
However, the known carbostyril derivatives having a side chain represented by the formula ##STR6## have had a drawback in that they increase circulation activities such as heart rate increasing activity and the like.